1. Field of the Invention
The present invention relates to a fluid-filled vibration damping device to be used for an automotive engine mount and the like and a method of manufacturing the same.
2. Description of the Related Art
Conventionally, there has been known a vibration damping device as a kind of vibration damping coupling body or a vibration damping supporting body interposed between the members constituting a vibration transmission system to connect the members to each other in a vibration damping manner, which is applied to an automotive engine mount and the like. Also, as one type of vibration damping device, a fluid-filled vibration damping device is proposed having a non-compressible fluid sealed therein for the purpose of further improving the vibration damping performance or the like. The fluid-filled vibration damping device, as described in U.S. Pat. No. 5,183,243, for example, has a structure where a first mounting member to be mounted to one member constituting the vibration transmission system and a second mounting member to be mounted to the other member constituting the same are elastically connected to each other by a main rubber elastic body. In addition, within the fluid-filled vibration damping device, a fluid chamber is formed to keep a non-compressible fluid sealed therein so as to exert a vibration damping effect based on the flow action of the fluid and the like.
By the way, the fluid-filled vibration damping device has a fluid chamber formed between the opposing faces of the main rubber elastic body and a flexible film by means of assembling in the non-compressible fluid a vulcanization-molded product of the flexible film and the vulcanization-molded product of the main rubber elastic body. Especially in U.S. Pat. No. 5,183,243, the fluid chamber is formed by having a tubular fitting member externally fitted and fixed onto a second mounting member through a drawing operation, for example, under a condition where the tubular fitting member fixed to the outer peripheral face of the flexible film is externally slipped around the second mounting member that is fixed to the outer peripheral face of the main rubber elastic body in the non-compressible fluid.
However, when the tubular fitting member externally slipped around the outer tubular member is subjected to the drawing operation in the non-compressible fluid, the space between the second mounting member and the tubular fitting member is closed with a sealing rubber layer in the initial stage of the drawing operation when the fixing force between the second mounting member and the tubular fitting member is still small. As a result, the internal pressure of the fluid chamber rises as the amount of diameter-constricting deformation of the tubular fitting member by the drawing thereof is increased, which poses a risk of tilting the second mounting member against the tubular fitting member or generating a positional deviation between them in the direction of detaching from each other during the assembly.
In assembling the tubular fitting member to the second mounting member by drawing, a jig is attached to restrain the flexible film to limit its deformation in order to properly set the amount of fluid sealed in the fluid chamber, so that no effect of liquid-pressure compensation due to deformation of the flexible film can be exerted. Also, when the assembly of the tubular fitting member to the second mounting member is performed without restraining the flexible film with a jig, the internal pressure rise of the fluid chamber is mitigated, while the amount of fluid sealed therein is varied to make it difficult to obtain the intended vibration damping performance in a stable manner.